Mobile operators worldwide have launched streaming real-time services (such as mobile TV and radio) over their existing 3G Universal Mobile Telecommunications System (UMTS) networks. However, the existing UMTS air-interface and overall network architecture are not adequate to deliver high quality, bandwidth-demanding multimedia content, such as television for a large number of users. Consequently, the 3GPP standards consortium identifies optimizations in the UTRAN and the core network system architecture that will allow the deployment of broadcasting-type applications over a UMTS air-interface and core network.
The add-on framework to the UMTS system architecture in a family of 3GPP specifications is called Multimedia Multicasting/Broadcasting Service (MBMS). The MBMS framework identifies the modifications needed in the UMTS Radio Access Network (RAN) and describes service aspects, such as security and charging in a set of 3GPP specifications (see, for example, references [1], [2], [4], [8]). 3GPP2 has defined a similar service in a family of specifications called Broadcast Multicast Service (BCMCS).
MBMS/BCMCS represents a point-to-multipoint service architecture defined in an end-to-end manner within the family of 3GPP/2 specifications that allow a 3G operator to deploy a broadcasting/multicasting service. For example, Mobile TV is deployed over its allocated spectrum by upgrading the existing network with the relevant 3GPP2 MBMS/BCMCS specifications.
MBMS/BCMCS multimedia streaming traffic and the associated uplink/downlink signaling are conventionally transmitted from the same network on the same frequency band. Because MBMS is intended to serve a large user population, the high volume of broadcast/multicast traffic and the number of processing nodes along its path impose a significant performance strain on the existing core network and UTRA elements of the UMTS network. For example, the core network mobility anchor (e.g., SGSN in 3GPP UMTS), and the radio network controller (e.g., RNC in 3GPP UMTS) must process and transport the “normal” point-to-point traffic generated by the different packet and circuit-switched applications. Therefore, a way to reduce the strain on the network is desired.